When opening a simple HTML document in Dreamweaver CS3 (Mac OSX 10.4.10) this afternoon I got this modal dialog pop up. Clicking Cancel or OK didn't close it, and had to force quit the application.

Never seen this happen before, and haven't been able to reproduce it since. A quick Google search seems to indicate this is some remnant from Fireworks or Freehand but don't have a definitive answer as of yet.